standards and guidelines for communication sites - Radio And ...

PERSONAL PROTECTIVE EQUIPMENT (PPE) APPENDIX A: ELECTROMAGNETIC ENERGY INFORMATION
• Warning
The warning sign denotes the boundary of areas with RF levels
substantially above the FCC limits, normally defined as those
greater than ten (10) times the Occupational/Controlled MPE.
Telecommunication contractors and employees shall not enter
these areas unless special procedures are followed. These
situations typically are associated with broadcast transmitters
operating at high power. If work is required in these areas, the
broadcast transmitter must be shut down for the duration of the
maintenance. Engineering evaluation must be performed to
determine the proper special procedures required before this area
can be entered.
A.6 PERSONAL PROTECTIVE EQUIPMENT (PPE)
A.6.1 PROTECTIVE CLOTHING
FIGURE A-14 WARNING
SIGN
There may be situations where field analysis shows areas that are not in compliance with the
Occupational/Controlled MPE. After all options are considered and if the situation cannot be controlled
with engineering or work practice solutions, implementation of Personal Protective Equipment (PPE)
may be the only solution. An example of this type of situation may be a rooftop that has collocated
broadcast in the vicinity of a heavily congested antenna field. In certain situations where building
architectural concerns are a priority there may be no simple solution available to reduce the fields. The
only solution may be the use of RF protective clothing as a means to reduce EME exposure.
RF protective clothing was introduced into the United States several years ago by a German
manufacturer (NSP) 1 and sold under the name Naptex. The suit consists of work coveralls with an
integral hood for head protection. The suit is constructed of a polyester yarn, which is wound coaxially
around stainless steel fibers. This provides uniform consistency of material and attenuating metal.
Tests 2,3 have shown that the suit can effectively provide between 10 dB and 12 dB of reduction in EME
absorption within the body at virtually any frequency over the telecommunications spectrum. This
would indicate that use of the suit could compensate for exposure to EME fields as great as 1000%
above the FCC Occupational/Controlled MPE values. Additional testing has shown the use of the suit
without the hood in fields under 300% of the Occupational/Controlled MPE values at 900 MHz
provides compliance with the peak SAR limits of 8 W/kg. The acceptable levels that the hoodless suit
can be safely used increase as the frequency is reduced. Contractors shall be notified if RF Protective
Clothing or the hood is required for compliance.
1. See NSP Website: www.nspworldwide.com
2. Tell, R. A. (1995). Engineering Services for Measurement and Analysis of Radio frequency (RF) Fields.
Technical report for the Federal Communication Commission, Office of Engineering and Technology,
Washington, DC, FCC/OET RTA 95-01 [NTIS order no. PB95-253829].
3. Tell, R. A. (1996). SAR Evaluation of the Naptex suit for use in VHF and UHF bands. Presented at the
International RF Safety Workshop, Schwangau, Germany, September 25-26.
A-26 68P81089E50-B 9/1/05